This invention relates to a manufacturing method of a magnetic medium such as a magnetic recording medium or a recording head, in more detail, relates to a method of forming a protection film for a recording layer of a magnetic recording mediums such as a magnetic tape, magnetic disc, magnetic card or an optical magnetic recording disc.
Also, it relates to a method of forming a protection film on recording part of a recording head such as a magnetic recording head for a VTR that records analog or digital signals or for a magnetic disc that records or erases digital or analog signals, or an optical magnetic recording head for an optical magnetic recording medium.
Magnetic recording mediums have so far been classified in two types, i.e. coating type and vacuum deposition type.
The method of coating type is to liquidize a mixture of magnetic powder of .gamma.-Fe.sub.2 O.sub.3 added with Fe.sub.2 O.sub.3 or Co in a mixture of polyvinyl-butylal, toluene, methylisobutyl, etc. and coat them on the surface of the body of the medium in the thickness of 4-5 .mu.m.
By this method, manufacture was easy but there was some limit in making the magnetic powder into fine particles, and therefore the performance was not good enough for high density recording.
On the other hand, in the case of deposition method, the recording density is better than the coating method, but, there is a weakness in durability because the magnetic metal layer is exposed. Accordingly, overcoating is applied to 1000-2000 .ANG. metal which is vacuum-evaporated by electron beam or spattering depositation technique, and some lubricant is applied to the magnetic recording medium to give lubricity. Nevertheless, sufficient durability has not been achieved as yet. In addition, as the overcoating and lubricity can not be applied thinly and uniformly, the gap between the recording layer and the head becomes larger, thus the high density-recording can not be obtained the vacuum evaporation and deposition technique.
As to recording heads, in manufacturing recording heads for conventional VTRs, floppy discs, and the like, such methods are generally used that a magnetic film is formed by deposition on the surface of a body of ceramics, another ceramic layer is placed thereon and the portion thereof that contacts the medium is cut after grinding, and special surface treatment was not made for abrasion-resistance, though grinding at the portion contacting the medium was made. The abrasion-resistance was improved merely by changing the ceramic materials alone.
As a result, conventional recording heads have been apt to damage recording mediums, be very abrasive, and be less reliable.
In view of the faults of the conventional methods mentioned above, the purpose of this invention is to provide a method to form a lubricant layer on a surface of a recording medium or on a recording head thinly and uniformly, without pinholes, to improve the reliability of a recording medium, to realize high density recording, to reduce damage by a head to a recording medium, as well as to improve the reliability of a recording head itself.